A release candidate (RC) means we think we’re done, but with millions of users and thousands of plugins and themes, it’s possible we’ve missed something. In fact, we did miss some things in RC1 and RC2. This third release candidate was not originally scheduled, but due a number of defects uncovered through your testing of RC2 (thank you!), we are putting out another 4.9 release candidate.

We hope to ship WordPress 4.9 on Tuesday, November 14 (that’s tomorrow) at 23:00 UTC, but we still need your help to get there. If you haven’t tested 4.9 yet, now is the time! If there are additional defects uncovered through testing between now and the release time, we may delay the 4.9 release to the following day.

We’ve made just over 20 changes since releasing RC2 last week (as we did between RC1 and RC2). For more details about what’s new in version 4.9, check out the Beta 1, Beta 2, Beta 3, Beta 4, RC1, and RC2 blog posts. A few specific areas to test in RC3:

Switching between the Visual and Text tabs of the editor, and the syncing of the cursor between those two tabs.

Overriding linting errors in the Customizer’s Additional CSS editor.

Adding nav menu items for Custom Links in the Customizer.

Scheduling customization drafts (stubbed posts/pages) for publishing in the Customizer.

Autosave revisions for changes in the Customizer.

About page styling.

Developers, please test your plugins and themes against WordPress 4.9 and update your plugin’s Tested up to version in the readme to 4.9. If you find compatibility problems please be sure to post to the support forums so we can figure those out before the final release — we work hard to avoid breaking things. Please see the summative field guide to the 4.9 developer notes on the core development blog.